Fix short raycasts missing large objects

[appgurueu]

Increases the tolerance from one node to five nodes. Also optimizes the "sphere" used for pre-filtering entities to start in the middle of the line segment rather than at the start.

Fixes #14337

How to test

See the issue. Note: The mod depends on futil and fmod (mods by flux, available on CDB). Alternatively, you can modify it to use particles (which I find slightly nicer), and also use that to look at the raycasts:

diff --git a/init.lua b/init.lua
index 53177e5..a71925f 100644
--- a/init.lua
+++ b/init.lua
@@ -30,15 +30,26 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 	player:set_wielded_item(wielded_item)
 end)
 
+local function add_marker(pos, color)
+	minetest.add_particle({
+		pos = pos,
+		texture = "short_raycast_waypoint.png^[multiply:" .. color,
+		expirationtime = 60,
+		size = 1,
+	})
+end
+
 local function multicast(start, stop, objects, liquids, step)
 	local pos = start
 	local delta = (stop - start):normalize() * step
+	add_marker(pos, "red")
 	local function get_next_ray()
 		local old_pos = pos
 		pos = pos + delta
 		if start:distance(pos) > start:distance(stop) then
 			return
 		end
+		add_marker(pos, "red")
 		return Raycast(old_pos, pos, objects, liquids)
 	end
 	local ray = get_next_ray()
@@ -72,13 +83,7 @@ minetest.register_tool("short_raycast:caster", {
 
 		for pt in multicast(start, start + (100 * look), true, false, step) do
 			if pt.type ~= "object" or pt.ref ~= user then
-				futil.create_ephemeral_hud(user, 60, {
-					hud_elem_type = "image_waypoint",
-					text = "short_raycast_waypoint.png",
-					scale = { x = -1 / 16 * 9, y = -1 },
-					alignment = { x = 0, y = -1 },
-					world_pos = pt.intersection_point,
-				})
+				add_marker(pt.intersection_point, "white")
 				break
 			end
 		end

It should look something like this:

[fluxionary]

The mod depends on futil and fmod

oh whoops, i copied that code without noticing the dependency. i'll replace it with your particles.

[grorp]

Makes sense, haven't tested